A tool is shown having a cross beam assembly made of beams joined by a center box structure. The assembly is adapted to be mounted by brackets to the outer end of a cylindrical case. The center box structure has a vertical shaft rotatably mounted therein and extending beneath the assembly. Secured to the vertical shaft is a radius arm which is adapted to rotate with the shaft. On the longer end of the radius arm is a measuring tip which contacts the cylindrical surface to be measured and which provides an electric signal representing the radius of the cylindrical surface from the center of rotation of the radius arm. An electric servomotor rotates the vertical shaft and an electronic resolver provides an electric signal representing the angle of rotation of the shaft. The electric signals are provided to a computer station which has software for its computer to calculate and print out the continuous circumference profile of the cylindrical surface, and give its true diameter and the deviations from the ideal circle

Currie, James R.

Kissel, Ralph R.

Oliver, Charles E.

Redmon, John W., Sr.

Smith, Earnest C.

Swanson, Charles P.

Wallace, Charles C.

English

NASA Technical Reports Server

NASA CASE NO. M F S -
PRINT FIGURE /
NOTICE
The invention disclosed in this document resulted from
research in aeronautical and space activities performed under
programs of the National Aeronautics and Space Administration.
The invention is owned by NASA and is, therefore, available for
licensing in accordance with the NASA Patent Licensing
Regulation (14 Code of Federal Regulations 1245.2).
To encourage commercial utilization of NASA-owned inventions,
it is NASA policy to grant licenses to commercial concerns.
Although NASA encourages nonexclusive licensing to promote
competition and achieve the widest possible utilization, NASA
will consider the granting of a limited exclusive license,
pursuant to the NASA Patent Licensing Regulations, when such a
license will provide the necessary incentive to the licensee to
achieve early practical application of the invention.
Address inquiries and all applications for license for this
invention to NASA Patent Counsel, Marshall Space Flight Center,
Mail Code CCO1, Huntsville, AL 35812. Approved NASA forms for
application for nonexclusive or exclusive license are available
from the above address. . -
MSFC
C (tfASfl-Case-iiFS-28287- 1) CILJSDBICAL SURFACE N88-23959
EKOFI1E AND DJAKEIEB BEASOEJKG TCOI AND
«ITBCD Patent Application (KASA) 17 p
CSCL 14B DDclas
G3/35 0145753
https://ntrs.nasa.gov/search.jsp?R=19880014575 2020-03-20T07:00:34+00:00Z
MFS-28287-1
TECHNICAL ABSTRACT
Cylindrical Surface Profile and Diameter Measuring Tool
and Method
The invention is directed to a tool .and method for
measuring and recording the profile and diameter of a
cylindrical surface at great accuracy.
Fig. 1 shows the tool as having a cross beam assembly 15
that fits onto the cylindrical case 11 that has a cylindrical
surface to be measured. A movable radius arm 28 is rotatably
mounted beneath the assembly 15. The radius arm 28 is driven
by a servomotor gear train 49 and has a resolver 61 that
provides an electrical signal representative of the relative
position of the arm 28. The distal end of the radius arm 28
from its rotation center has a digital linear gauge 46 (Fig.
2) feature which is biased by a constant pressure to contact
the cylindrical surface 44 and follow it as the radius arm 28
rotates. The electrical signals from the resolver 61 and
linear gauge 46 are provided to a computer system 73 by which
an offset circle based on the true diameter of the cylindrical
case surface is plotted together with case profile deviations
therefrom. The tool therefore does not depend upon having the
radius arm rotation center at the precise axial center of the
cylindrical surface.
For large diameter cylindrical cases, measurements have
herebefore been accomplished by manual techniques. While
measurement devices for measuring the internal diameter of
tubes with linear gauges have been used such devices depended
on having the rotating radius arm at the precise axial center
of the cylinder. The present invention does not depend on
knowing the location of the axial center of the cylindrical
case, and the rotation center of the radius arm may be offset
therefrom.
Inventors: James R. Currie, Ralph R. Kissel, Earnest C.
Smith, Charles E. Oliver, and John W. Redmon, Sr.
of the George C. Marshall Space Flight Center
and Charles C. Wallace and Charles P.
Swanson of Teledyne Brown Engineering,
Subcontract P,.O. 018514, Contract NAS8-36300
Serial No. 122,740
Filed: November 18, 1987
F1G.1
61
44
'
FIG.2
87
FIG.4
107 08
FIG.6
FIG.5
NASA Case No. MFS-28287-1 PATENT
CYLINDRICAL SURFACE PROFILE AND DIAMETER MEASURING
TOOL AND METHOD
ORIGIN OF THE INVENTION
05 The invention described herein was made in the
performance of work under a NASA contract and is subject
to the provisions .of Section 305 of the National
Aeronautics and Space Act of 1958, Public Law 85-568 (72
Stat. 435, 42 U.S.C. 2457).
10 TECHNICAL FIELD
This invention relates to a tool and method for measuring
and recording the profile and diameter of a cylindrical
surface at great accuracy,. and more particularly to a
tool and method for measuring the profile and diameter of
15 surfaces of large cylindrical objects such as solid
rocket motor cases in which the axis center is not
precisely known.
BACKGROUND ART
Measurement of large diameter cylindrical cases has
20 herebefore been accomplished by essentially manual
techniques which while adequate for construction type
activities do not meet the needs for assembling together
large segmented cylindrical cases of solid rocket motors.
A need exists for continuous profile information of the
25 cylindrical surfaces of adjacent segments that were to be
joined together. The out-of-roundness of a rocket motor
case segment is not necessarily objectionable if the
adjacent case segments that were to be joined were
similarly out-of-round. Manually performing measurements
30 to support such a profile for a rocket motor case segment
would literally run into thousands of measurements and
have a significant possibility of human error.
While apparatus for simply measuring the diameter of an
internal cylindrical surface has been accomplished, as
shown by U. S. Patent No. 4,521,968, with, a radius arm
with a linear transducer, such apparatus depends on
05 having the rotating radius arm at the precise axis center
of the cylinder that is defined by the cylindrical
surface.
STATEMENT OF THE INVENTION
The present invention provides a device or tool having a
10 cross beam assembly that fits onto the cylindrical case
and includes a movable radius measuring arm that rotates
and detects continuously the profile of the cylindrical
surface relative to the rotation center of the arm. The
radius arm is driven by a servomotor gear train and has a
15 resolver that provides electrical signals of the relative
position of the arm. The distal end of the radius arm
from its rotational center has a digital linear gauge
which is biased by a constant pressure to contact the
cylindrical surface to be profiled and thus follow it as
20 the radius arm rotates, all the time providing an
electrical signal of the relative location of the
cylindrical surface. The electrical signals from the
resolver and linear gauge are provided to a computer
system by which' an offset circle based on the true
25 diameter of ' the cylindrical case surface measured is
plotted together with case profile deviations therefrom.
Accordingly, it is an object of the present invention to
provide an automated cylindrical profile and diameter
measuring tool and method that works easily and with
30 great accuracy...
Another object is to provide a cylindrical profile and
diameter measuring tool that may be positioned on
cylindrical cases easily without regard to the radius
\
3center of the cylindrical case and is essentially
portable so it may be placed on cylindrical cases
regardless of their relative orientation.
Yet another object is to provide a cylindrical" profile
05 and diameter measuring tool which is not dependent on
knowing the exact, physical location of the radius c.enter
of that cylindrical surface.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a pictorial view of the cylindical surface and
10 diameter measuring tool of the present invention.
FIG. 2 is an enlarged side view showing the movable
radius arm assembly association with the main cross beam
structure, some parts shown in section.
FIG. 3 is a partial view showing the slidable end
15 structure of a the main cross beam structure taken along
line 3-3 of FIG. 1.
FIG. 4 is a top view of the lower center housing tray
plate fixed to the radius arm and rotating shaft and
showing the coiling of the electrical wire to permit the
20 rotation of the arm, taken along line 4-4 of FIG. 2.
FIG. 5 is a partial top view of the upper center housing
plate covering the lower center plate of FIG. 4 and fixed
to the cross beam structure and showing the stop and
switch actuator.
25 FIG. 6 is a view along line 6-6 of FIG. 5 showing the
mechanical stop.
DETAILED DESCRIPTION OF THE INVENTION
Referring to the drawings, FIG. 1 sho.ws a .large
cylindrical case 11 resting on a floor (not shown) and
extending through a hole 12" in a work platform 13. The
05 platform 13 is at^a level to provide access by workmen to
the open end of the cylindrical case 11. Mounted across
the open end of the case 11 is a cross beam structure 15
of the present invention that has brackets 16 secured by
bolts or the like to the outer surface of the cylindrical
10 case 11. In the drawings the cross beam structure 15 is
mounted by end brackets 16 to the clevis end of a solid
rocket rocket case segment 11, as shown best in FIGS. 2
and 3 •
The cross beam structure 15 is made of H-beams 18, 19,
15 20, 21 joined together by - a center box structure 23
which, as shown best in FIG. 2, has therein a vertical
shaft 25 rotatably mounted by bearing races 26. The lower
part of the vertical shaft 25 is joined to a radius arm
28 which is adapted to rotate with the shaft 25 and is
20 beneath the cross beam structure 15 for this particular
embodiment. The radius arm 28 is a box structure with a
end measurement tip 30 .secured to its end that is
specially designed for contacting the cylindrical surface
to be measured with a constant force. The opposite radius
25 arm end 31 extends only a short distance from the
rotating shaft center but has a slidable ring weight 32
thereon so as to counterbalance the weight of the longer
measuring radius arm end. As shown in FIG. 2, the end
measurement tip 30 is oriented to contact the outer
30 inside surface of the clevis of the solid rocket motor
case segment.
\
The measurement tip 30 is an assembly* consisting of a
supporting bracket 33 attached to the longer end of the
radius arm 28 which supports inturn a fixed member 34
having a ball race slide 35. Attached to the bottom of
the slide 35 is a channel member 36 that is connected by
its inside flange 37 with a negator spring 38 that
extends from and is wound onto a drum 39 se.cured to an
05 hanger member 40 extending down from supporting bracket
33- Thus as shown the negator spring 3# urges with a
constant force the channel member 36 which in Jihis
example has a lower extending support 41 having a support
roller 42 riding on the upper edge surface of the clevis
10 and a measurement wheel 43 rolling on the cylindrical
surface 44 to be measured. Thus, it can be seen that the
measurement wheel 43 is exerted against the cylindrical
surface 44 with a constant force by the action of the
negator spring 38 pulling on the channel member 36 which
15 moves with little friction because of the ball race
supported slide 35.
An essential element of the • measurement tip 30 is the
device to measure the movements of the channel member 36
and this is accomplished by an electronic linear gage 46
20 of a standard commercial type which has a biased plunger
shaft 47 which rides against the end flange 37 surface of
the channel member 36 and follows its movement back and
forth. The linear gage 46 provides a digital electrical
signal with respect to the position of the biased plunger
25 shaft 47 and therefore its signal can correlate to the
change in the cylindrical surface 44 being measured with
respect to the rotation center of the radius arm 28.
As also noted in FIG. 2 an electric servomotor 49 is
mounted within the flanges of crossbeam 15 which drives
30 a shaft 50 which drives a gear train (1,000 to 1 ratio)
52 which inturn drives through a slip clutch 53 and
another gearing box 54 a vertcal shaft 55 within an
housing 56. The housing 56 extends through a cut-out of
the upper flange in the crossbeam. The gearing box 54
35 transmits the horizontal rotation of the shaft from the
slip clutch 53 into a 90 degree change gearing box 54. A
pulley 57 is fixed to the upper end of the vertical shaft
55, which pulley 57 drives a belt 58 which rotates a
larger pulley 59 fixed to the vertical shaft 25 extending
from the center box structure 23 tying the crossbeams
05 together. An electronic resolver 61 of a standard
commercial type is mounted to a platform housing 62
extending above the larger pulley 59 for providing an
electric signal of the sine and cosine relationship of
the rotation angle of its shaft, which shaft is secured
!0 to the vertical, shaft 25 that drives the radius arm 28 in
its rotation. The drive mechanism described gives a
measuring speed at the end of the radius arm 28 of
approximate five inches per circumference per second.
The signal and power wires 64 for the linear gauge 46 are
15 fastened to the radius arm 28, as indicated in FIG. 2,
and are snaked through a protective tunnel 65 and tube 66
into the lower circular center tray plate 68 fastened to
the radius arm 28 and having its center corresponding (to
the axis of the housing vertical shaft 25. As shown best
20 in FIG. 4, the signal and power wire 64 is coiled within
the upper surface of the tray plate 68 so as to permit a
limited rotation of the radius arm 28 relative to the
fixed .crossbeam structure 15. The signal and power wire
64 exits from the upper center housing plate 70 and
25 extends within a tube 71 as indicated i'n FIG. 2 along the
crossbeam 18 holding the servomotor 49 to the computer
and printer station 73 which is shown on a portable cart
74. Other signal wires from the resolver 61 also exit
along the same crossbeam 18 in the same bundle of power
30 and signal wires 64 ..to the computer and printer station
73« The same crossbeam 18 carries the power line for the
electric servomotor 49, linear gauge 46, and electronic
shaft angle resolver 61.
Referring to FIG. 1 again, it should be noted that one
35 end of each of the two extended and perpendicular
crossbeams 18, 20 and 19, 21 is fixed to an adjustable
micrometer 78 of a standard design, shown best in FIG. 2,
which is able to shift that particular crossbeam a short
distance toward or away from its bracket support 16 by
the operator rotating a knob 80 on the operating shaft
05 81 . The other .-ends of the same respective extended
crossbeam 18, '20 and 19, 21 are slidably held to their
brackets 16, shown best in FIG. 3, by having.a flat_bar
extension 86 which slides to and fro within a tunnel
receptacle .8? having Teflon plates 88 to reduce the
10 friction. The flat bar extention 86 has an end lip 89 to
serve as a stop so it may not be pulled through the
receptacle 87. The adjustable support 86 permits the
center housing 23 of the crossbeam structure 15 relative
to the cylindrical casing being measured to be shifted a
15 short distance. Also, in this regard, as noted in FIG. 1
one half 19 of an extended crossbeam 19, 21 has its
flange width reduced which enables that crossbeam 19 to
flex slightly to relieve any strain caused by slight
misaligraents that the brackets 16 may introduced.
20 in operation the radius arm 28 only makes one 360 degree
rotation to provide the needed measurments for the
profile and diameter determinations. The power switch in
that regard is turned on and off by the computer of the
computer and printer station 73. As shown in FIG. 5 a cam
25 operated electrical switch 101 is mounted on the center
housing cover plate 70 and the cam 102 is mounted on the
edge of the center tray plate 68 which rotates with the
radius arm 18 about the housing shaft 25. The cam member
102. has a slot 103 to enable it to be adjusted relative
30 to the switch activator arms 104, 105. One switch arm 101
is activated during the counter-clockwise rotation and
the other switch arm 105 is activated on the return or
clockwise rotation. A mechanical stop as shown in FIG. 6
is also provided to prevent the overrun of the radius arm
35 except for a few degrees from one complete turn. It has a
pivoting dog leg 106 that .has an interfering fit with a
extending member 107 in one direction to stop rotation
8but permits the center tray plate 68 to rotate in the
opposite direction because the leg end is too short to
interfere with the other extending member 108.
The computer of the computer and printer station 73
05 receives the signals from linear gauge 46 which by adding
the known distance of the radius arm 28 length gives.the
radius length of the cylindrical surface 44 being
measured. The location of the radius arm 28 relative to
the cylindrical surface is determined by the electrical
!0 resolver 61 signal, which gives the angle rotation of
the radius arm, to the computer. Thus, it can be seen
that the profile of the cylindrical surface of the
cylindrical surface can be determined based on the radius
arm center and readily be printed in chart form from
15 basic calculations. However, the data also provides the
basis of determining the true center of the cylindrical
surface by offset circle calculations using the least
square curve fit. In practice, the computer software is
such as to provide in chart form the continuous
20 circumference profile and radius of the cylindrical
surface, its diameter, its maximum plus deviation and its
maximum negative deviation from an ideal circle based on
the calculated radius. Thus, it can be seen that the
profile and diameter measuring tool described need not be
25
 located at the exact center of the cylindical circle to
obtain the profile information needed which is a great
aid in the setting up of the tool for measurment.
It is now apparent that a tool and method has been
described that can .measure the diameter of a large
30 cylinder with great accuracy. In the use of the tool and
method for measuring solid rocket ca^e segments it is now
practical to match those segments which are substantially
of the same roundness and profile. The roundness data can
be used to determine shim thickness and interference fit
35 between adjacent segments. Also, the segment case can be
squeezed while the tool is set up thereon to more closely
achieve a certain roundness and the results may be
quickly checked by operation of the tool. Further the
measurement tip of the radius arm may be of different
shapes and configurations to best fit -.against the
05 cylindrical surface. The tool can as readily measure the
cylindrical surface of a case segment hanging from a
hoist as it can when the case segment is sitting o,n a
surface.
While the, invention has been described relative to a
!0 specific embodiment, it is evident that medications and
changes may be made with regard thereto without departing
from the scope of the claims.
What is claimed is:
CYLINDRICAL SURFACE PROFILE AND DIAMETER MEASURING
TOOL AND METHOD
ABSTRACT
A tool is shown having a cross beam assembly (15) made of
05 beams (18, 19, 20, 21) joined by a center box structure
(23). The assembly (15) is adapted to be mounted by
brackets (16) to the outer end of a cylindrical case
(11). The center box structure (23) has a vertical shaft
(25) rotatably mounted therein and extending beneath the
10 assembly (15). Secured to the vertical shaft (25) is a
radius arm (28) which is adapted to rotate with shaft
(25). On the longer end- of the radius arm (28) is a
measuring tip (30) which contacts the cylindrical surface
to be measured and which provides an electric signal
15 representing the radius of the cylindrical surface from
the center of rotation of the radius arm (28). An
electric servomotor (49) rotates the vertical shaft (25)
and an electronic resolver (61) provides an electric
signal representing the angle of rotation of the shaft
20
 (25). The electric signals are provided to a computer
station (73) which has software for its computer to
calculate and print out the continuous circumference
profile of the cylindrical surface, and give its true
diameter and the deviations from the ideal circle.


Cylindrical surface profile and diameter measuring tool and method

Cylindrical surface profile and diameter measuring tool and method

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